This invention relates to an air vent control apparatus, more particularly to an air vent control apparatus which interrupts an unwanted external force applied to a louver blade and which prevents the force from being transmitted to the motor.
A conventional air vent control apparatus is shown in FIGS. 4 and 5. The control unit ( not shown ) transmits to a stepping motor 7 a signal which is determined according to indoor temperature so that the air direction is controlled. The stepping motor 7 rotates a driving crank arm 8 upward or downward. The rotative force is transmitted to a link 10 connected with the driving crank arm 8 so that the link 10 moves upward or downward. Accordingly, first and second driven crank arms 5 and 6 connected to the upper and middle part of the link 10, respectively, are rotated by the rectilinear movement of the link 10, and finally first and second blades 2 and 3 are rotated to a certain angle in order to control the direction of the air flow.
However, if any rotative force external to the air control system is applied to at least one blade 2 and/or 3, the stepping motor 7 becomes unable to rotate the driving crank arm 8 in accordance with the signal transmitted from the control unit because the unwanted external force is transmitted to the driving shaft 7A of the stepping motor 7. As a result, the air direction determined by the first and second blades 2 and 3 is changed, even after the external force is removed. In addition, if the external force is applied frequently, the life time of the stepping motor 7 will be shortened, and also the stepping motor 7 may become damaged or ineffective.
The Korean Patent Application No. 92-100087 (1992, Jun. 10), names the same inventor as the present invention, disclosed one solution for the above problems as shown in FIGS. 6 to 8. As a motor 27 operates, a crank arm 27A having a free end situated in a slide perforation 30C of a link 30 is rotated. A first slide member 31 and a second slide member 32 are provided above and below the free end of the crank arm 27A, respectively. The first and second slide members 31 and 32 are interconnected by a resilient member 34. Protrusions 30E are affixed to the link 30. When the free arm is rotated, its free end moves in a circular pattern. For example, when that free end moves downwardly, it pushes the second slide 32 downwardly, and the second slide 32 pulls the first slide 31 downwardly, due to their interconnection by the spring 34. The first slide engages the protrusions 30E to displace the link 30 downwardly. Since the free end of the crank arm 27A moves in a circular pattern, it causes the link 30 to oscillate about a pivot connection between the link and a louver crank arm 26. Thus, the link 30 undergoes a compound movement in that it moves vertically (upwardly or downwardly) and simultaneously oscillates about an axis at its lower end. Only the vertical movement results in an adjustment of the louvers. Another louver crank arm 25 disposed above the crank arm 26 has its free end mounted in a slot of the link 30 to accommodate oscillation of the link 30. The vertical motion of the link 30 produces a rotational movement of crank arms 25 and 26 which are connected to louvers 22 and 23, respectively, so that the louvers blades 22 and 23 move within the predetermined range. When an incidental force is applied to the louver(s) 22 or 23, the crank arms 25 or 26 are rotated and the link 30 is moved in the direction of arrow "A". Protrusions 30E, push the second slide member 32 in the direction of the arrow "A". Hence, the first slide member 31 bearing against the upper portion of the crank arm 27A remains stationary position and the resilient member 34 is extended. Therefore, the external force applied to the louver 22 or 23 is not transmitted to the crank arm 27A, thereby preventing the movement of the motor 27 from being interrupted. Further, when the external force is no longer applied, the link 30 is moved upward by the restoring force of the resilient member 34. The louver 22 and 23 return to the intended position.
Because the above air vent control apparatus is operated through a arrangement of components, the whole structure is complicated, and consumes excessive space. Also, since an excessive number of parts are used, the efficiency is lowered and the production costs are increased.